The iPhone is finally available for sale in China Mobile stores after Apple spent years negotiating for a deal with the carrier, the world’s largest by subscriber number. In a sign of how important the partnership is to Apple, CEO Tim Cook showed up at the China Mobile launch today to meet customers, pose for pictures, and autograph iPhones.

China Mobile has 740 million subscribers, but competing carriers China Unicom and China Telecom have already carried the iPhone 5s and 5c since September. As The Next Web points out, China Mobile subsidies are also pricier. For example, China Mobile users can get a 16GB iPhone 5s for free if they commit to a 24-month plan for about $97 per month, or they can pay about $625 for the same phone if they get a 24-month contract for $31 per month. But China Unicom subscribers get an iPhone 5s for free when they commit to a 30-month contract for $63 per month. China Telecom users also get a free iPhone 5s by signing up for a 24-month contract at $64 per month.

China Mobile’s contracts are less attractive than its two competitors, but it can afford to charge a premium partly because it uses a TD-LTE standard for its 4G networks, making its network speedier than its two competitors.

So far, the deal appears to be paying off for Apple. Earlier this week, Cook said that Apple sold more iPhones in the Greater China region than it has at any time previously, which means it moved over 10.4 million iPhones there after selecting China as an iPhone launch market for the first time ever. The China Mobile deal will also bring the iPhone to cities where it was previously unavailable, with the devices now sold in 3,000 more locations.

Cook also said he was unconcerned about competition from inexpensive Android devices, stating that 57% of mobile browsing in China happens on iOS hardware. But Android devices already hold a 66% market share, according to research firm Umeng, and there is still plenty of room left for growth in China’s mobile market, especially as more users in China’s “second-tier” cities buy their first smartphone. Android smartphones cost just an average of $233, so Apple still has plenty of competition even with the China Mobile deal.